Chondroblastoma Differential Diagnoses

Updated: Sep 25, 2020
  • Author: Timothy A Damron, MD; Chief Editor: Omohodion (Odion) Binitie, MD  more...
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Diagnostic Considerations

Chondromyxoid fibromas, which are found in patients in the same age group in which chondroblastomas are found, may mimic the latter radiographically and microscopically. Both types of lesions tend to have well-circumscribed lytic areas on radiographs, microscopically seen areas of immature cartilage and giant cells, and perilesional marrow edema on magnetic resonance imaging (MRI). However, chondromyxoid fibromas most often arise from the metaphysis or metadiaphysis rather than from the epiphysis (where 90% of chondroblastomas are located), are devoid of calcification, and have a characteristic myxoid, pseudolobular pattern of organization, as well as more pleomorphic stellate cells.

Giant cell tumors of bone also may mimic chondroblastomas; the epiphyseal location and histologic characteristics can be quite similar. However, the former are almost exclusively seen in patients who are skeletally mature, whereas chondroblastomas tend to arise in skeletally immature patients. Furthermore, the epicenter of a giant cell tumor lies within the metaphysis. On histologic examination, giant cell tumors have elongated cells that are clustered together, in contrast to the round or polygonal cells of chondroblastoma. Calcifications and chondroid matrix also are absent in giant cell tumors. 

Eosinophilic granuloma is a lesion found in young patients that may appear in rare instances as a radiolucent epiphyseal lesion similar to chondroblastoma. However, microscopic examination reveals a more heterogeneous collection of cells, including histiocytes, granulocytes, and eosinophils.

Chondroblastomalike osteosarcoma may be confused with chondroblastoma. [16]

Finally, clear cell chondrosarcoma may have features that overlap those of chondroblastoma, but the presence of large cells with abundant clear cytoplasm and vesicular nuclei, as well as type II collagen and malignant chondrocytes, should distinguish this tumor. Typically, clear cell chondrosarcoma is an epiphyseal tumor of adulthood. 

Although an epiphyseal or apophyseal location is classic for chondroblastoma and extension into the metaphysis may be seen, purely metaphyseal or diaphyseal chondroblastomas have been reported. A series of seven such cases suggests that they follow the same pediatric age distribution as their classic counterparts and, apart from their unusual location, have similar radiographic features, including extensive perilesional edema on MRI. [17]  Biopsy is still required to confirm the diagnosis, and treatment remains the same.

Differential Diagnoses